Portable 1900mAh External Backup Battery Charger Power Bank Case for iPhone 4 4S (White) iPhone 4 4S 4G external battery charging case. Full body coverage protection for your iPhone. Works as both an extended iPhone battery and a protection case. Lightweight, thin design. Non slip comfort grip. Rechargeable lithium polymer. Capacity: 1900 mAh. Output voltage: DC 5V. Output current: 500mA max. ON/OFF Button for Optional Power Output Control. Four LED lights indicates the power level remaining the case (Each light represents 25% of remaining power). Sleek, Low-Profile design; Rechargeable up to 1000 times.